Probably not, but a significant chunk of people who will use the wagon when the server resets are not going to have any idea if the borders are open again, anyway.
I guess this is the grim consequence. Anyway, not to spoil it, but when and if you learn why the borders were closed in the first place, you're going to laugh.
So that's something to look forward to.
No idea if DMs can create dialogue options on NPCs but I agree that it would have been nice to have a sign fixed on the wagon or something which said "Borders Closed, Travel Not Possible" or something like that. A player carpenter will probably have to do it, despite the fact it's technically ignoring NPCs.